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[AArch64][GlobalISel] Don't bail out of folding in extends into WRO addressing modes.

Authored by aemerson on May 22 2020, 3:32 PM.



We were doing an additional check to see if a G_SEXT is worth folding into a mem op compared to SelectionDAG. In terms of code size it's usually a wash.

I'm not entirely sure this is the right thing to do, I don't have performance numbers to show any difference with this either way.

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aemerson created this revision.May 22 2020, 3:32 PM

Is this only for code size? Does SDAG do this at, say, -O3?

The GISel version of the function has a check for minsize, but SDAG has a check against shouldOptForSize() in its version of this function (AArch64DAGToDAGISel::isWorthFolding)

We're also missing a couple cases that are present in the SDAG version of the function. Adding them might make this fire.

aemerson abandoned this revision.Mon, Aug 10, 10:47 PM

Abandon this for now, not enough justification.